Manufacture of turbine or compressor blades



April 10, 1962 P. e. TURNER MANUFACTURE OF TURBINE OR COMPRESSOR BLADES Filed Aug. 28, 1957 By Attorney United States Patent T 3,028,661 MANUFACTURE OF TURBINE R COMPRESSOR BLADES Philip George Turner, Worcestershire, England, assignor to The International Nickel Company, Inc., New York, N.Y., a corporation of Delaware Filed Aug. 28, 1957, Ser. No. 681,876 Claims priority, application Great Britain Sept, 3, 1956 4 Claims. (Cl. 29-156.8)

The present invention relates to the production of turbine blades and, more'particularly, to the production of turbine blades having both integral roots and shrouds.

It is well known that turbine or compressor blades, must sometimes consist of a root, a blade proper of airfoil or similar section and a shroud (or end platform). It is convenient to mak e the blades by extrusion but it is not possible in practice to form both a blade and a shroud while the blade proper is extruded through a die of airfoil or like section. 'One or other (in practice the root) can be roughly formed simultaneously with the blade by using an extrusioncontainer of appropriate dimensions, extruding the blade from it through a die and stopping the extrusion while enough metal remains in the container to form the root (or shroud) but both root and shroud cannot be made in this way.

Although many attempts were made to overcome the foregoing difficulties and other disadvantages, none, as far as I am aware, was entirely successful when carried into practice commercially on an industrial scale.

It has now been discovered that by a combination of processes a turbine blade having both an integral root and shroud may be made.

It is an object of the present invention to provide a process for the production of a turbine blade having both an integral root and an integral shroud.

Other objects and advantages will become apparent from the following descripton taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a view of an airfoil turbine blade segment having a plurality of filled holes extending therethrough;

FIG. 2 depicts the same segment which has been flattened and thereafter slotted in accordance with an embodiment of the invention;

FIG. 3 shows the slotted segment which has been folded back to form a shroud as contemplated by the invention;

FIG. 4 illustrates the segment of FIG. 1 which has been flattened and hollowed in accordance with another embodiment of the invention;

FIG. 5 is illustrative of the hollow segment of FIG. 4 after belling as contemplated by the invention; and

FIG. 6 shows the belied end of the segment in FIG. 5 after a flattening operation contemplated by the invention.

Generally speaking, the present invention contemplates a process-for the production of a turbine blade having both an integral root and an integral shroud which comprises at least partially extruding a billet of heat-resistant metal through an orifice of airfoil section; removing said partially extruded billet from the extrusion apparatus; longitudinally faulting or relieving said partially extruded billet centrally from the tip of the extruded portion of said billet to a point intermediate said tip and the unextruded portion of said billet by removing metal therefrom by a machining operation; and thereafter working the metal adjacent the fault outwardly to form an end portion substantially normal to and integral wtih the remaining portion of said billet.

According to the invention, an integral shroud and/or root is made by extruding a blade proper of length greater than is required, longitudinally faulting the exhereinbefore.

3,028,661 Patented Apr. 10, 1962 truded length by slotting at least one end of this along the major axis or forming in it a cavity extending along this axis for the excess distance and then working the metal on each side of the split or cavity outwards. In this manner, it is possible to retain in the finished workpiece the advantageous flow lines resulting from the ex-- trusion without substantially cutting into same. In carrying the invention into practice, it is preferre to form the integral root from the unextruded portion of the billet and to form the shroud in the manner disclosed The invention is particularly applicable to blades with longitudinal cooling passages (the tip ends of which are illustrated in the accompanyingdrawing), which can be formed by making longitudinal holes. in the metal to be extruded and filling these with a filler,

for example, an iron-manganese-titanium alloy or a metal moved by machining operations. If they are not initially in alignment, they may be brought into alignment by localized pressure and cut in the same way as depicted in FIG. 2 wherein the end of blade 12 has been deformed by flattening to align the holes and is then machined to form slot 13 which eliminates holes 11 in this portion of the blade. Thereafter, the sides 14 of blade 12 are folded outwards by a forging process to form the shroud 15 (shown in FIG. 3). Filled holes 11 remain in the blade and open through shroud 15. Alternatively, a continuous cavity 16 is formed in the end of blade 12 which has been deformed by flattening to align the holes as shown in FIG. 4. The metal surrounding cavity 16 is then opened or deformed by belling to form belled structure 17 shown in FIG. 5 and flat forging so as to form enlarged and flattened end 18 (shown in FIG. 6) which is suitable as a shroud. The filled holes 11 are advantageously converted into continuous cavity 16 over the desired length of the blade by spark erosion.

It is important that during any forging or similar operation the holes should be filled, since otherwise they tend to close up. Since it is not feasible to remove the filler only over the length which is to be worked outwards, the filler should be left in position until the working by forging or the like is complete.

If a thick shroud is desirable, the blade section may be extended to corresponding thickness and the surplus metal throughout the blade proper may be removed by machining. As another alternative, a completed extruded section may be provided with enlarged structures on both ends thereof by dual application of the process provided by the present invention.

With respect to the manufacture of turbine blades using the novel process of the present invention, it should be understood that the term heat-resistant metal is used to include austenitic nickel-chromium, nickel-chromium-iron, cobalt-nickel-chromium, cobalt-chromium and cobalt-chromium-iron alloys which contain at least about 25% nickel plus chromium, cobalt plus chromium or nickel plus chromium plus cobalt in addition to small amounts of aluminum, titanium, molybdenum, tungsten, niobium, tantalum, silicon, manganese, zirconium and boron which may optionally be present in the alloys.

The present invention is particularly applicable to the production of turbine rotor blades with shrouds, turbine stator blades with shrouds (and/or shrouds and roots) and to nozzle guide vanes with fastening platforms.

Althoughthe present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be re sorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim:

1. A process for the production of a hollow turbine blade having an enlarged portion on one end thereof and having longitudinal cooling passages extending therethrough, which comprises providing a billet of heat-resistant metal having longitudinal holes extending therethrough and having said holes filled with a filler having substantially the same deformation characteristics as said billet, at least partially extruding said billet through an airfoil section die in a direction substantially parallel to the direction of said filled holes to produce an extruded billet, Working the metal in at least one tip of the extruded portion of said extruded billet to align the filled holes in said tip in a line substantially across said extruded tip portion of said extruded billet, removing the filler and the centrally located metal adjacent said filler from said partially extruded billet at said tip along the line of said filled holes by machining so as to completely remove the filler from said tip, working the metal adjacent the metal which was removed by said machining operation laterally to form an end portion of said extruded billet substantially normal to and integral with the remaining portion of said extruded billet and thereafter removing the filler from said extruded billet.

2. A process as set forth and defined in claim 1 wherein 4 the billet is partially extruded to provide an extruded blade portion and an unextruded root portion.

3. A process as set forth and defined in claim 1 wherein the machining to remove filler and adjacent metal from the extruded and aligned tip end forms a slot and the metal adjacent said slot is worked laterally to form the end portion substantially normal to and integral with the remaining portion of said extruded billet.

4. A process as set forth and defined in claim 1 wherein the machining to remove filler and adjacent metal from the extruded and aligned tip end forms a cavity and the metal adjacent said cavity is belled and flared to form the end portion substantially normal to and integral with the remaining portion of said extruded billet.

References Cited in the file of this patent UNITED STATES PATENTS 941,375 Loud et a1 Nov. 30, 1909 2,405,897 Milone et a1 Aug. 13, 1946 2,638,663 Bartlett et a1 May 19, 1953 2,679,669 Kempe June 1, 1954 2,743,509 Friedman May 1, 1956 2,764,804 Arness Oct. 2, 1956 2,914,841 Graham Dec. 1, 1959 FOREIGN PATENTS 149,131 Australia Nov. 21, 1952 726,909 Great Britain Mar. 23, 1955 755,610 Great Britain Aug. 22, 1956 

